Bump map compositing for simulated digital painting effects

ABSTRACT

A method of compositing multiple images together so as to produce realistic effects is disclosed. The method comprises defining an image canvas bump map approximating a surface to be painted on; defining a painting bump map of a painting object to be painted on the surface; combining the image canvas bump map and the painting bump map to produce a final composited bump map. The step of combining utilises a stiffness factor, the stiffness factor determining a degree of modulation of the painting bump map by the image canvas bump map. The combining process can comprise low-pass filtering the image canvas bump map with the stiffness determining the degree of low-pass filtering. The application is particularly suited for utilization in a hand held camera device to produce instant images on demand having a brushed artistic interpretation.

CROSS REFERENCES TO RELATED APPLICATIONS

The following Australian provisional patent applications are hereby incorporated by cross-reference. For the purposes of location and identification, U.S. patent applications identified by their U.S. patent application Ser. Nos. (USSN) are listed alongside the Australian applications from which the U.S. patent applications claim the right of priority.

US PATENT/PATENT APPLICATION (CLAIMING CROSS-REFERENCED RIGHT OF PRIORITY AUSTRALIAN FROM AUSTRALIAN PROVISIONAL PATENT PROVISIONAL APPLICATION NO. APPLICATION) DOCKET NO. PO7991 09/113,060 ART01 PO8505 09/113,070 ART02 PO7988 09/113,073 ART03 PO9395 09/112,748 ART04 PO8017 09/112,747 ART06 PO8014 09/112,776 ART07 PO8025 09/112,750 ART08 PO8032 09/112,746 ART09 PO7999 09/112,743 ART10 PO7998 09/112,742 ART11 PO8031 09/112,741 ART12 PO8030 09/112,740 ART13 PO7997 09/112,739 ART15 PO7979 09/113,053 ART16 PO8015 09/112,738 ART17 PO7978 09/113,067 ART18 PO7982 09/113,063 ART19 PO7989 09/113,069 ART20 PO8019 09/112,744 ART21 PO7980 09/113,058 ART22 PO8018 09/112,777 ART24 PO7938 09/113,224 ART25 PO8016 09/112,804 ART26 PO8024 09/112,805 ART27 PO7940 09/113,072 ART28 PO7939 09/112,785 ART29 PO8501 09/112,797 ART30 PO8500 09/112,796 ART31 PO7987 09/113,071 ART32 PO8022 09/112,824 ART33 PO8497 09/113,090 ART34 PO8020 09/112,823 ART38 PO8023 09/113,222 ART39 PO8504 09/112,786 ART42 PO8000 09/113,051 ART43 PO7977 09/112,782 ART44 PO7934 09/113,056 ART45 PO7990 09/113,059 ART46 PO8499 09/113,091 ART47 PO8502 09/112,753 ART48 PO7981 09/113,055 ART50 PO7986 09/113,057 ART51 PO7983 09/113,054 ART52 PO8026 09/112,752 ART53 PO8027 09/112,759 ART54 PO8028 09/112,757 ART56 PO9394 09/112,758 ART57 PO9396 09/113,107 ART58 PO9397 09/112,829 ART59 PO9398 09/112,792 ART60 PO9399 6,106,147 ART61 PO9400 09/112,790 ART62 PO9401 09/112,789 ART63 PO9402 09/112,788 ART64 PO9403 09/112,795 ART65 PO9405 09/112,749 ART66 PP0959 09/112,784 ART68 PP1397 09/112,783 ART69 PP2370 09/112,781 DOT01 PP2371 09/113,052 DOT02 PO8003 09/112,834 Fluid01 PO8005 09/113,103 Fluid02 PO9404 09/113,101 Fluid03 PO8066 09/112,751 IJ01 PO8072 09/112,787 IJ02 PO8040 09/112,802 IJ03 PO8071 09/112,803 IJ04 PO8047 09/113,097 IJ05 PO8035 09/113,099 IJ06 PO8044 09/113,084 IJ07 PO8063 09/113,066 IJ08 PO8057 09/112,778 IJ09 PO8056 09/112,779 IJ10 PO8069 09/113,077 IJ11 PO8049 09/113,061 IJ12 PO8036 09/112,818 IJ13 PO8048 09/112,816 IJ14 PO8070 09/112,772 IJ15 PO8067 09/112,819 IJ16 PO8001 09/112,815 IJ17 PO8038 09/113,096 IJ18 PO8033 09/113,068 IJ19 PO8002 09/113,095 IJ20 PO8068 09/112,808 IJ21 PO8062 09/112,809 IJ22 PO8034 09/112,780 IJ23 PO8039 09/113,083 IJ24 PO8041 09/113,121 IJ25 PO8004 09/113,122 IJ26 PO8037 09/112,793 IJ27 PO8043 09/112,794 IJ28 PO8042 09/113,128 IJ29 PO8064 09/113,127 IJ30 PO9389 09/112,756 IJ31 PO9391 09/112,755 IJ32 PP0888 09/112,754 IJ33 PP0891 09/112,811 IJ34 PP0890 09/112,812 IJ35 PP0873 09/112,813 IJ36 PP0993 09/112,814 IJ37 PP0890 09/112,764 IJ38 PP1398 09/112,765 IJ39 PP2592 09/112,767 IJ40 PP2593 09/112,768 IJ41 PP3991 09/112,807 IJ42 PP3987 09/112,806 IJ43 PP3985 09/112,820 IJ44 PP3983 09/112,821 IJ45 PO7935 09/112,822 IJM01 PO7936 09/112,825 IJM02 PO7937 09/112,826 IJM03 PO8061 09/112,827 IJM04 PO8054 09/112,828 IJM05 PO8065 6,071,750 IJM06 PO8055 09/113,108 IJM07 PO8053 09/113,109 IJM08 PO8078 09/113,123 IJM09 PO7933 09/113,114 IJM10 PO7950 09/113,115 IJM11 PO7949 09/113,129 IJM12 PO8060 09/113,124 IJM13 PO8059 09/113,125 IJM14 PO8073 09/113,126 IJM15 PO8076 09/113,119 IJM16 PO8075 09/113,120 IJM17 PO8079 09/113,221 IJM18 PO8050 09/113,116 IJM19 PO8052 09/113,118 IJM20 PO7948 09/113,117 IJM21 PO7951 09/113,113 IJM22 PO8074 09/113,130 IJM23 PO7941 09/113,110 IJM24 PO8077 09/113,112 IJM25 PO8058 09/113,087 IJM26 PO8051 09/113,074 IJM27 PO8045 6,110,754 IJM28 PO7952 09/113,088 IJM29 PO8046 09/112,771 IJM30 PO9390 09/112,769 IJM31 PO9392 09/112,770 IJM32 PP0889 09/112,798 IJM35 PP0887 09/112,801 IJM36 PP0882 09/112,800 IJM37 PP0874 09/112,799 IJM38 PP1396 09/113,098 IJM39 PP3989 09/112,833 IJM40 PP2591 09/112,832 IJM41 PP3990 09/112,831 IJM42 PP3986 09/112,830 IJM43 PP3984 09/112,836 IJM44 PP3982 09/112,835 IJM45 PP0895 09/113,102 IR01 PP0870 09/113,106 IR02 PP0869 09/113,105 IR04 PP0887 09/113,104 IR05 PP0885 09/112,810 IR06 PP0884 09/112,766 IR10 PP0886 09/113,085 IR12 PP0871 09/113,086 IR13 PP0876 09/113,094 IR14 PP0877 09/112,760 IR16 PP0878 09/112,773 IR17 PP0879 09/112,774 IR18 PP0883 09/112,775 IR19 PP0880 6,152,619 IR20 PP0881 09/113,092 IR21 PO8006 6,087,638 MEMS02 PO8007 09/113,093 MEMS03 PO8008 09/113,062 MEMS04 PO8010 6,041,600 MEMS05 PO8011 09/113,082 MEMS06 PO7947 6,067,797 MEMS07 PO7944 09/113,080 MEMS09 PO7946 6,044,646 MEMS10 PO9393 09/113,065 MEMS11 PP0875 09/113,078 MEMS12 PP0894 09/113,075 MEMS13

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to digital image processing and in particular to bump map compositing.

BACKGROUND OF THE INVENTION

The present invention relates to the production of digital imaging effects. Available products such as Adobe's Photoshop (trade mark) provide for the creation of complex images having multiple layers which are combined by means of compositing, to form a final image.

In the field of creation of 3D imaging effects, it is known to provide for a bump map so as to produce the effect of a 3 dimensional surface during compositing. The process of bump mapping is thought to have been originally developed by Blinn “Simulation of Wrinkled Surfaces”, Computer Graphics, 12 (3), at pages 86-92.

Unfortunately, when utilising the bump mapping process, it is difficult to combine multiple images together, with each image having its own bump map, into a final image. In particular, when producing imaging effects that simulate the process of painting an image with the brush strokes on a canvas, it would be desirable to be able to composite the brush strokes on the canvas so as to produce a 3 dimensional surface texture effect that automatically approximates that which would be produced by an artist.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide for a method of compositing multiple images together so as to produce realistic effects.

In accordance with the first aspect of the present invention there is provided a method of combining image bump maps to simulate the effect of painting on an image, the method comprising:

defining an image canvas bump map approximating the surface to be painted on;

defining a painting bump map of a painting object to be painted on said surface;

combining said image canvas bump map and said painting bump map to produce a final composited bump map utilising a stiffness factor, said stiffness factor determining the degree of modulation of said painting bump map by said image canvas bump map.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIGS. 1 and 2 illustrate a brush bump map;

FIGS. 3 and 4 illustrate a background canvas bump map;

FIGS. 5 and 6 illustrate the process of combining bump maps.

FIG. 7 illustrates a background of the map;

FIGS. 8 and 9 illustrate the process of combining bump maps in accordance with the preferred embodiment; and

FIG. 10 illustrates a flowchart of a preferred embodiment of the invention.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

The preferred embodiment is preferably implemented through suitable programming of a hand held camera device such as that described in Australian Provisional Patent Application No. PO7991 filed Jul. 15, 1997 entitled “Image Processing Method and Apparatus (ART01)”, in addition to Australian Provisional Patent Application entitled “Image Processing Method and Apparatus (ART01a)” filed concurrently herewith by the present applicant, the content of which is hereby specifically incorporated by cross reference.

The aforementioned patent specifications disclose a camera system, hereinafter known as an “Artcam” type camera, wherein sensed images can be directly printed out by an internal Artcam portable camera unit. Further, the aforementioned specification discloses means and methods for performing various manipulations on images captured by the camera sensing device leading to the production of various effects in any output image. The manipulations are disclosed to be highly flexible in nature and can be implemented through the insertion into the Artcam of cards having encoded thereon various instructions for the manipulation of images, the cards hereinafter being known as “Artcards”. The Artcam further has significant onboard processing power by an Artcam Central Processor unit (ACP) which is interconnected to a memory device for the storage of important data and images.

The preferred embodiment will be discussed with reference to the process of “painting” an image onto a canvas utilising simulated brush strokes. It is assumed that bump maps techniques are utilised and, in particular, each image utilised has an associated bump map defining a texture of the surface of the image.

In FIG. 1, there is illustrated an example round brush stroke bump map 1; with FIG. 2 illustrating a corresponding section through the line A-A′ of FIG. 1 and includes a general profile 3 of the surface of the generally round brush stroke 1.

It is assumed that it is desired to render a brush stroke having a bump map as illustrated in FIG. 1 onto a generally hessian shaped “canvas” image whose bump map is as illustrated in FIG. 3 with again, the height through the line B-B′ being illustrated in FIG. 4. The height consisting of a series of undulating peaks eg. 6.

In the preferred embodiment, the bump maps of FIG. 2 and FIG. 4 are combined to produce a final bump map in a variable manner in accordance with a supplied stiffness factor. The stiffness factor being designed to approximate the effects of using a “stiff” or “flexible” paint. In FIG. 5, there is illustrated the example of a combination of the two bumps of FIG. 2 and 4 wherein they are combined for a brush paint having a high stiffness. In FIG. 6, there is illustrated example of a combination of the two bump maps of FIGS. 2 and 4 when a low stiffness paint has been utilised.

In the preferred embodiment, when combining bump maps, the bump maps are not simply added, since the brush stroke which consists of paint will have a certain plasticity and will therefore fill in depressions in the background. Hence, in order to achieve the effects of FIGS. 5 and 6, the brush stroke bump map is added to a low-pass filtered version of the background bump map. The low-pass filter has its radius determined by a paint stiffness factor. The higher the stiffness factor, the wider the filter radius and hence the less the background surface texture showing through. The low-pass filter radius can also be scalable by the relative brush stroke thickness so the filtered background surface texture will converge with the actual background surface texture where the brush stroke thins to nothing ie. mostly along the edges.

Turning now to FIGS. 7 and 8, there is shown an example of this process with FIG. 7 illustrating the initial background bump map. In FIG. 8, there is shown the combined background bump maps with FIG. 8 showing a high stiffness paint 12 on top of a low-pass filtered version of the bump map 11 with FIG. 9 showing a low stiffness paint 14 on top of the low-pass filtered bump map 13.

FIG. 10 illustrates the steps involved in creating a composite bump map from a plurality of individual bump maps.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal ink jet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per printhead, but is a major impediment to the fabrication of pagewidth printheads with 19,200 nozzles.

Ideally, the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new ink jet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systems described below with differing levels of difficulty. Forty-five different ink jet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table under the heading Cross References to Related Applications.

The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems.

For ease of manufacture using standard process equipment, the printhead is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the printhead is 100 mm long, with a width which depends upon the ink jet type. The smallest printhead designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The printheads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the printhead by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The printhead is connected to the camera circuitry by tape automated bonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of ink jet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. These are designated IJ01 to IJ45, which match the docket numbers in the table under the heading Cross References to Related Applications.

Other ink jet configurations can readily be derived from these forty-five examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into ink jet printheads with characteristics superior to any currently available ink jet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, a print technology may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Thermal An electothermal Large force High power Canon Bubblejet bubble heater heats the ink to generated Ink carrier 1979 Endo et al GB above boiling point, Simple limited to water patent 2,007,162 transferring significant construction Low efficiency Xerox heater-in- heat to the aqueous No moving parts High pit 1990 Hawkins et ink. A bubble Fast operation temperatures al U.S. Pat. No. 4,899,181 nucleates and quickly Small chip area required Hewlett-Packard forms, expelling the required for actuator High mechanical TIJ 1982 Vaught et ink. stress al U.S. Pat. No. 4,490,728 The efficiency of the Unusual process is low, with materials required typically less than Large drive 0.05% of the electrical transistors energy being Cavitation causes transformed into actuator failure kinetic energy of the Kogation reduces drop. bubble information Large print heads are difficult to fabricate Piezo- A piezoelectric crystal Low power Very large area Kyser et al U.S. Pat. No. electric such as lead consumption required for actuator 3,946,398 lanthanum zirconate Many ink types Difficult to Zoltan U.S. Pat. No. (PZT) is electrically can be used integrate with 3,683,212 activated, and either Fast operation electronics 1973 Stemme expands, shears, or High efficiency High voltage U.S. Pat. No. 3,747,120 bends to apply drive transistors Epson Stylus pressure to the ink, required Tektronic ejecting drops. Full pagewidth IJ04 print heads impractical due to actuator size Requires electric poling in high field strengths during manufacture Electro- An electric field is Low power Low maximum Seiko Epson, strictive used to activate consumption strain (approx. Usui et all JP electrostriction in Many ink types 0.01%) 253401/96 relaxor materials such can be used Large area IJ04 as lead lanthanum Low thermal required for actuator zirconate titanate expansion due to low strain (PLZT) or lead Electric field Response speed magnesium niobate strength required is marginal (˜10 (PMN). (approx. 3.5 V/μm) μs) can be generated High voltage without difficulty drive transistors Does not require required electrical poling Full pagewidth print heads impractical due to actuator size Ferro- An electric field Low power Difficult ot IJ04 electric used to induce a phase consumption integrate with transition between the Many ink types electronics antiferroelectric (AFE) can be used Unusual and ferroelectric (FE) Fast operation materials such as phase. Perovskite (<1 μs) PLZSnT are materials such as tin Relatively high required modified lead longitudinal strain Actuators require lanthanum zirconate High efficiency a large area titanate (PLZSnT) Electric field exhibit large strains of strength areound 3 up to 1% associated V/μm can be readily with the AFE to FE provided phase transition. Electro- Conductive plates are Low power Difficult to IJ02, IJ04 static plates seperated by a consumption operate electrostatic compressible or fluid Many ink types devices in an dielectric (usually air). can be used aqueous Upon application of a Fast operation environment voltage, the plates The electrostatic attract each other and actuator will displace ink, causing normally need to be drop ejection. The seperated from the conductive plates may ink be in a comb or Very large area honeycomb structure, required to achieve or stacked to increase high forces the surface area and High voltage therefore the force. drive transistors may be required Full pagewidth print heads are not competitive due to actuator size Electro- A strong electric field Low current High voltage 1989 Satio et al, static pull is applied to the ink, consumption required U.S. Pat. No. 4,799,068 on ink whereupon Low temperature May be damaged 1989 Miura et al, electrostatic attraction by sparks due to air U.S. Pat. No. 4,810,954 accelerates the ink breakdown Tone-jet towards the print Required field medium. strength increases as the drop size decreases High voltage drive transistors required Electrostatic field attracts dust Permanent An electromagnet Low power Complex IJ07, IJ10 magnet directly attracts a consumption fabrication electro- permanent magnet, Many ink types Permanent magnetic displacing ink and can be used magnetic material casuing drop ejection. Fast operation such as Neodymium Rare earth magnets High efficiency Iron Boron (NdFeB) with a field strength Easy extension required. areound 1 Tesla cna be from single nozzles High local used. Examples are: to pagewidth print currents required Samarium Cobalt heads Copper (SaCo) and magnetic metalization should materials in the be used for long neodymium iron boron electromigration family (NdFeB, lifetime and low NdDyFeBNb, resistivity NdDyFeB, etc) Pigmented inks are usually infeasible Operating temperature limited to the Curie temperature (around 540 K) Soft A solenoid included a Low power Complex IJ01, IJ05, IJ08, magnetic magnetic field in a soft consumption fabrication IJ10, IJ12, IJ14, core electro- magnetic core or yoke Many ink types Materials not IJ15, IJ17 magnetic fabricated from a can be used usually present in a ferrous material such Fast operation CMOS fab such as as electroplated iron High efficiency NiFe, CoNiFe, or alloys such as CoNiFe Easy extension CoFe are required [1], CoFe, or NiFe from single nozzles High local alloys. Typically, the to pagewidth print currents required soft magnetic material heads Copper is in two parts, which metalization should are normally held be used for long apart by a spring. electromigration When the solenoid is lifetime and low actuated, the two parts resistivity attract, displacing the Electroplating is ink. required High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1]) Lorenz The Lorenz force Low power Force acts as a IJ06, IJ11, IJ13, force acting on a current consumption twisting motion IJ16 carrying wire in a Many ink types Typically, only a magnetic field is can be used quarter of the utilized. Fast operation solenoid length This allows the High efficiency provides force in a magnetic field to be Easy extension useful direction supplied externally to from single nozzles High local currents required the print head, for to pagewidth print currents required example with rare heads Copper earth permanent metalization should magnets. be used for long Only the current electromigration carrying wire need to be lifetime and low fabricated on the print- resisitivity head, simplifying Pigmented inks materials are usually requirements. infeasible Magneto- The actuator uses the Many ink types Force acts as a Fischenbeck, striction giant magnetostrictive can be used twisting motion U.S. Pat. No. 4,032,929 effect of materials Fast operation Unusual IJ25 such as Terfenol-D (an Easy extension materials such as alloy of terbium, from single nozzles Terfenol-D are dysprosium and iron to pagewidth print required developed at the Naval heads High local Ordnance Laboratory, High force is currents required hence Ter-Fe-NOL). available Copper For best efficiency, the metalization should actuator should be pre- be used for long stressed to approx. 8 electromigration MPa. lifetime and low resistivity Pre-stressing may be required Surface Ink under positive Low power Requires Silverbrook, EP tension pressure is held in a consumtion supplementary force 0771 658 A2 reduction nozzle by surface Simple to effect drop related patent tension. The surface construction seperation applications tension of the ink is No unusual Requires special reduced below the materials required in ink surfactants bubble threshold, fabrication Speed may be causing the ink to High efficiency limited by surfactant egress from the Easy extension properties nozzle. from single nozzles to pagewidth print heads Viscosity The ink viscosity is Simple Requires Silverbrook, EP reduction locally reduced to construction supplementary force 0771 658 A2 and select which drops are No unusual to effect drop related patent to be ejected. A materials required in seperation applications viscosity reduction can fabrication Requires special be achieved Easy extension ink viscosity electrothermally with from single nozzles properties most inks, but special to pagewidth print High speed is inks can be engineered heads difficult to achieve for 100:1 viscosity Requires reduction. oscillating ink pressure A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave is Can operate Complex drive 1993 Hadimioglu generated and without a nozzle circuitry et al, EUP 550,192 focussed upon the plate Complex 1993 Elrod et al, drop ejection region. fabrication EUP 572,220 Low effiency Poor control of drop position Poor control of drop volume Thermo- An actuator which Low power Efficient aqueous IJ03, IJ09, IJ17, elastic bend relies upon differential consumption operation requires a IJ18, IJ19, IJ20, actuator thermal expansion Many ink types thermal insulator on IJ21, IJ22, IJ23, upon Joule heating is can be used the hot side IJ24, IJ27, IJ28, used. Simple planar Corrosion IJ29, IJ30, IJ31, fabrication prevention can be IJ32, IJ33, IJ34, Small chip area difficult IJ35, IJ36, IJ37, required for each Pigmented inks IJ38, IJ39, IJ40, actuator may be infeasible, IJ41 Fast opertaion as pigmented particles High efficiency may jam the bend CMOS actuator compatible voltages and currents Standard MEMS processes can be used Easy extension from single nozzles to pagewidth print heads High CTE A material with a very High force can Requires a special IJ09, IJ17, IJ18, thermo- high coefficient of be generated material (e.g. PTFE) IJ20, IJ21, IJ22, elastic thermal expansion Three methods of Requires a PTFE IJ23, IJ24, IJ27, actuator (CTE) such as PTFE deposition are deposition process, IJ28, IJ29, IJ30, polytetrafluorotheylene under development: which is not yet IJ31, IJ42, IJ43, (PTFE) is used. As chemical vapor standard in ULSI IJ44 high CTE material deposition (CVD), fabs are usually non- spin coating, and PTFE deposition fabricated from a PTFE is a cannot be followed conductive material is candidate for low temperature (above incorporated. A 50 μm dielectric constant 350° C.) processing long PTFE bend insulation in ULSI Pigmented inks actuator with Very low power may be infeasible, polysilicon heater and consumption as pigmented particles 15 mW power input Many ink types may jam the bend can provide 180 μN can be used actuator force and 10 μm Simple planar deflection. Actuator fabrication motions include: Small chip area Bend required for each Push actuator Buckle Fast operation Rotate High efficiency CMOS compatible voltages and currents Easy extension from single nozzles to pagewidth print heads Conductive A polymer with a high High force can Requires special 1J24 polymer coefficient of thermal be generated materials thermo- expansion (such as Very low power development (High elastic PTFE) is doped with consumption CTE conductive actuator conducting substances Many ink types polymer) to increase its can be used Requires a PTFE conductivity to about 3 Simple planar deposition process, orders of magnitude fabrication which is not yet below that of copper. Small chip area standard in ULSI The conducting required for each fabs polymer expands actuator PTFE deposition when resistively Fast operation cannot be followed heated. High efficiency with high Examples of CMOS temperature (above conducting dopants compatible voltages 350° C.) processing include: and currents Evaporation and Carbon nanotubes Easy extension CVD deposition Metal fibers from single nozzles techniques cannot Conductive polymers to pagewidth print be used such as doped heads Pigmented inks polythiophene may be infeasible, Carbon granules as pigment particles may jam the bend actuator Shape A shape memory alloy High force is Fatigue limits IJ26 memory such as TiNi (also available (stresses maximum number alloy known as Nitinol- of hundreds of MPa) of cycles Nickel Titanium alloy Large strain is Low strain (1%) developed at the Naval available (more than is required to extend Ordnance Laboratory) 3%) fatigue resistance is thermally switched High corrosion Cycle rate between its weak resistance limited by heat martensitic state and Simple removal its high stiffness construction Requires unusual austenic state. The Easy extension materials (TiNi) shape of the actuator from single nozzles The latent heat of in its martensitic state to pagewidth print transformation must is deformed relative to be provided heads the austenic shape. Low voltage High current The shape change operation operation causes ejection of a Requires pre- drop. stressing to distort the martensitic state Linear Linear magnetic Linear Magnetic Requires unusual IJ12 Magnetic actuators include the actuators can be semiconductor Actuator Linear Induction constructed with materials such as Actuator (LIA), Linear high thrust, long soft magnetic alloys Permanent Magnet travel, and high (e.g. CoNiFe) Synchronous Actuator efficiency using Some varieties (LPMSA), Linear planar also require Reluctance semiconductor permanent magnetic Synchronous Actuator fabrication materials such as (LRSA), Linear techniques Neodymium iron Switched Reluctance Long actuator boron (NdFeB) Actuator (LSRA), and travel is available Requires the Linear Stepper Medium force is complex multi- Actuator (LSA). available phase drive circuitry Low voltage High current operation operation

BASIC OPERATION MODE Description Advantages Disadvantages Examples Actuator This is the simplest Simple operation Drop repetition Thermal inkjet directly mode of operation: the No external rate is usually Piezoelectric ink pushes ink actuator directly fields required limited to around 10 jet supplies sufficient Satellite drops kHz. However, this IJ01, IJ02, IJ03, kinetic energy to expel can be avoided if is not fundamental IJ04, IJ05, IJ06, the drop. The drop drop velocity is less to the method, but is IJ07, IJ09, IJ11, must have a sufficient than 4 m/s related to the refill IJ12, IJ14, IJ16, velocity to overcome Can be efficient, method normally IJ20, IJ22, IJ23, the surface tension. depending upon the used IJ24, IJ25, IJ26, actuator used All of the drop IJ27, IJ28, IJ29, kinetic energy must IJ30, IJ31, IJ32, be provided by the IJ33, IJ34, IJ35, actuator IJ36, IJ37, IJ38, Satellite drops IJ39, IJ40, IJ41, usually form if drop IJ42, 1343, IJ44 velocity is greater than 4.5 m/s Proximity The drops to be Very simple print Requires close Silverbrook, EP printed are selected by head fabrication can proximity between 0771 658 A2 and some manner (e.g. be used the print head and related patent thermally induced The drop the print media or applications surface tension selection means transfer roller reduction of does not need to May require two pressurized ink). provide the energy print heads printing Selected drops are required to separate alternate rows of the separated from the ink the drop from the image in the nozzle by nozzle Monolithic color contact with the print print heads are medium or a transfer difficult roller. Electro- The drops to be Very simple print Requires very Silverbrook, EP static pull printed are selected by head fabrication can high electrostatic 0771 658 A2 and on ink some manner (e.g. be used field related patent thermally induced The drop Electrostatic field applications surface tension selection means for small nozzle Tone-Jet reduction of does not need to sizes is above air pressurized ink). provide the energy breakdown Selected drops are required to separate Electrostatic field separated from the ink the drop from the may attract dust in the nozzle by a nozzle strong electric field. Magnetic The drops to be Very simple print Requires Silverbrook, EP pull on ink printed are selected by head fabrication can magnetic ink 0771 658 A2 and some manner (e.g. be used Ink colors other related patent thermally induced The drop than black are applications surface tension selection means difflcult reduction of does not need to Requires very pressurized ink). provide the energy high magnetic fields Selected drops are required to separate separated from the ink the drop from the in the nozzle by a nozzle strong magnetic field acting on the magnetic ink. Shutter The actuator moves a High speed (>50 Moving parts are IJ13, IJ17, IJ21 shutter to block ink kHz) operation can required flow to the nozzle. The be achieved due to Requires ink ink pressure is pulsed reduced refill time pressure modulator at a multiple of the Drop timing can Friction and wear drop ejection be very accurate must be considered frequency. The actuator Stiction is energy can be very possible low Shuttered The actuator moves a Actuators with Moving parts are IJ08, IJ15, IJ18, grill shutter to block ink small travel can be required IJ19 flow through a grill to used Requires ink the nozzle. The shutter Actuators with pressure modulator movement need only small force can be Friction and wear be equal to the width used must be considered of the grill holes. High speed (>50 Stiction is kHz) operation can possible be achieved Pulsed A pulsed magnetic Extremely low Requires an IJ10 magnetic field attracts an ‘ink energy operation is external pulsed pull on ink pusher’ at the drop possible magnetic field pusher ejection frequency. An No heat Requires special actuator controls a dissipation materials for both catch, which prevents problems the actuator and the the ink pusher from ink pusher moving when a drop is Complex not to be ejected. construction

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages Disadvantages Examples None The actuator directly Simplicity of Drop ejection Most inkjets, fires the ink drop, and construction energy must be including there is no external Simplicity of supplied by piezoelectric and field or other operation individual nozzle thermal bubble. mechanism required. Small physical actuator IJ01, IJ02, IJ03, size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24, IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36, IJ37, IJ38, IJ39, 1340, IJ41, 1342, 1343, IJ44 Oscillating The ink pressure Oscillating ink Requires external Silverbrook, EP ink pressure oscillates, providing pressure can provide ink pressure 0771 658 A2 and (including much of the drop a refill pulse, oscillator related patent acoustic ejection energy. The allowing higher Ink pressure applications stimul- actuator selects which operating speed phase and amplitude IJ08, IJ13, IJ15, ation) drops are to be fired The actuators rnust be carefully IJ17, IJ18, IJ19, by selectively may operate with controlled IJ21 blocking or enabling much lower energy Acoustic nozzles. The ink Acoustic lenses reflections in the ink pressure oscillation can be used to focus chamber must be may be achieved by the sound on the designed for vibrating the print nozzles head, or preferably by an actuator in the ink supply. Media The print head is Low power Precision Silverbrook, EP proximity placed in close High accuracy assembly required 0771 658 A2 and proximity to the print Simple print head Paper fibers may related patent medium. Selected construction cause problems applications drops protrude from Cannot print on the print head further rough substrates than unselected drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation. Transfer Drops are printed to a High accuracy Bulky Silverbrook, EP roller transfer roller instead Wide range of Expensive 0771 658 A2 and of straight to the print print substrates can Complex related patent medium. A transfer be used construction applications roller can also be used Ink can be dried Tektronix hot for proximity drop on the transfer roller melt piezoelectric separation. inkjet Any of the IJ series Electro- An electric field is Low power Field strength Silverbrook, EP static used to accelerate Simple print head required for 0771 658 A2 and selected drops towards construction separation of small related patent the print medium. drops is near or applications above air Tone-Jet breakdown Direct A magnetic field is Low power Requires Silverbrook, EP magnetic used to accelerate Simple print head magnetic ink 0771 658 A2 and field selected drops of construction Requires strong related patent magnetic ink towards magnetic field applications the print medium. Cross The print head is Does not require Requires external IJ06, IJ16 magnetic placed in a constant magnetic materials magnet fieId magnetic field. The to be integrated in Current densities Lorenz force in a the print head may be high, current carrying wire manufacturing resulting in is used to move the process electromigration actuator. problems Pulsed A pulsed magnetic Very low power Complex print IJ10 magnetic field is used to operation is possible head construction fleId cyclically attract a Small print head Magnetic paddle, which pushes size materials required in on the ink. A small print head actuator moves a catch, which selectively prevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description Advantages Disadvantages Examples None No actuator Operational Many actuator Thermal Bubble mechanical simplicity mechanisms have Ink jet amplification is used. insufficient travel, IJO1, IJ02, IJ06, The actuator directly or insufficient force, IJ07, IJ16, IJ25, drives the drop to efficiently drive IJ26 ejection process. the drop ejection process Differential An actuator material Provides greater High stresses are Piezoelectric expansion expands more on one travel in a reduced involved IJ03, IJ09, IJ17, bend side than on the other. print head area Care must be IJ18, IJ19, IJ20, actuator The expansion may be taken that the IJ21, IJ22, IJ23, thernaal, piezoelectric, materials do not IJ24, IJ27, IJ29, magnetostrictive, or delaminate IJ30, IJ31, IJ32, other mechanism. The Residual bend IJ33, IJ34, IJ35, bend actuator converts resulting from high IJ36, IJ37, IJ38, a bigh force Iow travel temperature or high IJ39, IJ42, IJ43, actuator mechanism to stress during IJ44 high travel, Iower formation force mechanism. Transient A trilayer bend Very good High stresses are IJ40, IJ41 bend actuator where the two temperature stability involved actuator outside layers are High speed, as a Care must be identical. This cancels new drop can be taken that the bend due to ambient fired before heat materials do not temperature and dissipates delaminate residual stress. The Cancels residual actuator only responds stress of formation to transient heating of one side or the other. Reverse The actuator loads a Better coupling Fabrication IJ05, IJ11 spring spring. When the to the ink complexity actuator is turned off, High stress in the the spring releases. spring This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Actuator A series of thin Increased travel Increased Some stack actuators are stacked. Reduced drive fabrication piezoelectric inkjets This can be voltage complexity IJ04 appropriate where Increased actuators require high possibility of short electric field strength, circuits due to such as electrostatic pinholes and piezoelectric actuators. Multiple Multiple smaller Increases the Actuator forces IJ12, IJ13, IJ18, actuators actuators are used force available from may not add IJ20, IJ22, IJ28, simultaneously to an actuator linearly, reducing IJ42, IJ43 move the ink. Each Multiple efficiency actuator need provide actuators can be only a portion of the positioned to control force required. ink flow accurately Linear A linear spring is used Matches low Requires print IJ15 Spring to transform a motion travel actuator with head area for the with small travel and higher travel spring high force into a requirements longer travel, lower Non-contact force motion. method of motion transformation Coiled A bend actuator is Increases travel Generally IJ17, IJ21, IJ34, actuator coiled to provide Reduces chip restricted to planar IJ35 greater travel in a area implementations reduced chip area. Planar due to extreme implementations are fabrication difficulty relatively easy to in other orientations. fabricate. Flexure A bend actuator has a Simple means of Care must be IJ10, IJ19, IJ33 bend small region near the increasing travel of taken not to exceed actuator fixture point, which a bend actuator the elastic limit in flexes much more the flexure area readily than the Stress remainder of the distribution is very actuator. The actuator uneven flexing is effectively Difficult to converted from an accurately model even coiling to an with finite element angular bend, resulting analysis in greater travel of the actuator tip. Catch The actuator controls a Very low Complex IJ10 small catch. The catch actuator energy construction either enables or Very small Requires external disables movement of actuator size force an ink pusher that is Unsuitable for controlled in a bulk pigmented inks manner. Gears Gears can be used to Low force, low Moving parts are IJ13 increase travel at the travel actuators can required expense of duration. be used Several actuator Circular gears, rack Can be fabricated cycles are required and pinion, ratchets, using standard More complex and other gearing surface MEMS drive electronics methods can be used. processes Complex construction Friction, friction, and wear are possible Buckle plate A buckle plate can be Very fast Must stay within Hirata et al, used to change a slow movement elastic limits of the “An Ink-jet Head actuator into a fast achievable materials for Iong Using Diaphragm motion. It can also device life Microactuator”, convert a high force, High stresses Proc. IEEE MEMS, low travel actuator involved Feb. 1996, pp 418- into a high travel, Generally high 423. medium force motion power requirement IJ18, 1127 Tapered A tapered magnetic Linearizes the Complex IJ14 magnetic pole can increase magnetic construction pole travel at the expense force/distance curve of force. Lever A lever and fulcrum is Matches low High stress IJ32, IJ36, IJ37 used to transform a travel actuator with around the fulcrum motion with small higher travel travel and high force requirements into a motion with Fulcrum area has longer travel and no linear movement, lower force. The lever and can be used for can also reverse the a fluid seal direction of travel. Rotary The actuator is High mechanical Complex IJ28 impeller connected to a rotary advantage construction impeller. A small The ratio of force Unsuitable for angular deflection of to travel of the pigmented inks the actuator results in actuator can be a rotation of the matched to the impeller vanes, which nozzle requirements push the ink against by varying thc stationary vanes and number of impeller out of the nozzle. vanes Acoustic A refractive or No moving parts Large area 1993 Hadimioglu lens diffractive (e.g. zone required et al, EUP 550,192 plate) acoustic lens is Only relevant for 1993 Elrod et al, used to concentrate acoustic inkjets EUP 572,220 sound waves. Sharp A sharp point is used Simple Difficult to Tone-jet conductive to concentrate an construction fabricate using point electrostatic field. standard VLSI processes for a surface ejecting ink- jet Only relevant for electrostatic ink jets

ACTUATOR MOTION Disad- Description Advantages vantages Examples Volume The volume of the Simple High en- Hewlett- expansion actuator changes, construction ergy is Packard pushing the ink in all in the case of typically Thermal directions. thermal ink required to Ink jet jet achieve Canon volume Bubblejet expansion. This leads to thermal stress, cavitation, and ko- gation in thermal ink jet imple- mentations Linear, The actuator moves in Efficient High fab- IJ01, IJ02, normal to a direction normal to coupling to rication IJ04, IJ07, chip the print head surface. ink drops complex- IJ11, IJ14 surface The nozzle is typically ejected ity may be in the line of normal to the required to movement. surface achieve perpen- dicular motion Parallel to The actuator moves Suitable for Fabri- IJ12, IJ13, chip parallel to the print planar cation IJ15, IJ33, surface head surface. Drop fabrication complex- , IJ34, ejection may still be ity Fric- IJ35, IJ36 normal to the surface. tion Stiction Membrane An actuator with a The effective Fabri- 1982 push high force but small area of the cation Howkins area is used to push a actuator be- complex- USP stiff membrane that is comes the ity Actua- 4,459,601 in contact with the ink. membrane tor size area Difficulty of inte- gration in a VLSI process Rotary The actuator causes Rotary levers Device IJ05, IJ08, the rotation of some may be used complex- IJ13, IJ28 element, such a grill or to increase ity May impeller travel have fric- Small chip tion at a area re- pivot point quirements Bend The actuator bends A very small Requires 1970 when energized. This change in the actua- Kyser et al may be due to dimensions tor to be USP differential thermal can be con- made from 3,946,398 expansion, verted to a at least 1973 piezoelectric large motion. two dis- Stemme expansion, tinct lay- USP magnetostriction, or ers, or to 3,747,120 other form of relative have a IJ03, IJ09, dimensional change. thermal IJ10, IJ19, difference IJ23, IJ24, across the IJ25, IJ29, actuator IJ30, IJ31, IJ33, IJ34, IJ35 Swivel The actuator swivels Allows oper- Inefficient IJ06 around a central pivot. ation where coupling This motion is suitable the net linear to the ink where there are force on the motion opposite forces paddle is applied to opposite zero Small sides of the paddle, chip area e.g. Lorenz force. requirements Straighten The actuator is Can be used Requires IJ26, IJ32 normally bent, and with shape careful straightens when memory al- balance of energized. loys where stresses to the austenic ensure that phase is the quie- planar scent bend is accurate Double The actuator bends in One actuator Difficult IJ36, IJ37, bend one direction when can be used to make IJ38 one element is to power two the drops energized, and bends nozzles. ejected by the other way when Reduced both bend another element is chip size. directions energized. Not sensitive identical. to ambient A small temperature efficiency loss com- pared to equivalent single bend actuators. Shear Energizing the Can increase Not 1985 actuator causes a shear the effective readily Fishbeck motion in the actuator travel of applicable USP material. piezoelectric to other 4,584,590 actuators actuator mech- anisms Radial The actuator squeezes Relatively High force 1970 constric- an ink reservoir, easy to required Zoltan tion forcing ink from a fabricate Inefficient USP constricted nozzle. single Difficult 3,683,212 nozzles from to inte- glass tubing grate with as macro- VLSI scopic processes structures Coil/ A coiled actuator Easy to Difficult IJ17, IJ21, uncoil uncoils or coils more fabricate as to fabri- IJ34, IJ35 tightly. The motion of a planar cate for the free end of the VLSI non-planar actuator ejects the ink. process devices Small area Poor out- required, of-plane therefore stiffness low cost Bow The actuator bows (or Can increase Maximum IJ16, IJ18, buckles) in the middle the speed of travel IJ27 when energized. travel is con- Mechanic strained ally rigid High force required Push-Pull Two actuators control The structure Not IJ18 a shutter. One actuator is pinned at readily pulls the shutter, and both ends, so suitable the other pushes it. has a high for ink jets out-of-plane which rigidity directly push the ink Curl A set of actuators curl Good fluid Design IJ20, IJ42 inwards inwards to reduce the flow to the complex- volume of ink that region be- ity they enclose. hind the actuator increases efficiency Curl A set of actuators curl Relatively Relatively IJ43 outwards outwards, pressurizing simple large chip ink in a chamber construction area surrounding the actuators, and expelling ink from a nozzle in the chamber. Iris Multiple vanes enclose High High fab- IJ22 a volume of ink. These efficiency rication simultaneously rotate, Small chip complex- reducing the volume area ity Not between the vanes. suitable for pig- mented inks Acoustic The actuator vibrates The actuator Large area 1993 Had- vibration at a high frequency. can be physi- required imioglu cally distant for effic- et al, from the ink ient oper- EUP ation at 550,192 useful fre- 1993 El- quencies rod et al, Acoustic EUP coupling 572,220 and cross- talk Com- plex drive circuitry Poor con- trol of drop vol- ume and position None In various ink jet No moving Various Silver- designs the actuator parts other brook, EP does not move. tradeoffs 0771 658 are re- A2 and quired to related eliminate patent moving applica- parts tions Tone-jet

NOZZLE REFILL METHOD Disad- Description Advantages vantages Examples Surface This is the normal way Fabrication Low speed Thermal tension that ink jets are simplicity Surface ink jet refilled. After the Operational tension Piezoelectric actuator is energized, simplicity force ink jet it typically returns relatively IJ01-IJ07, rapidly to its normal small IJ10-IJ14, position. This rapid compared IJ16, IJ20, return sucks in air to actuator IJ22-IJ45 through the nozzle force opening. The ink Long surface tension at the refill time nozzle then exerts a usually small force restoring dominates the meniscus to a the total minimum area. This repetition force refills the nozzle. rate Shutter- Ink to the nozzle High speed Requires IJ08, IJ13, ed os- chamber is provided at Low actuator common IJ15, IJ17, cillating a pressure that energy, as ink pres- IJ18, IJ19, ink oscillates at twice the the actuator sure os- IJ21 pressure drop ejection need only cillator frequency. When a open or May not drop is to be ejected, close the be suitable the shutter is opened shutter, for pig- for 3 half cycles: drop instead of mented ejection, actuator ejecting the inks return, and refill. The ink drop shutter is then closed to prevent the nozzle chamber emptying during the next negative pressure cycle. Refill After the main High speed, Requires IJ09 actuator actuator has ejected a as the nozzle two in- drop a second (refill) is actively dependent actuator is energized. refilled actuators The refill actuator per nozzle pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again. Positive The ink is held a slight High refill Surface Silverbrook, ink positive pressure. rate, there- spill must EP 0771 658 pressure After the ink drop is fore a high be pre- A2 and re- ejected, the nozzle drop repeti- vented lated patent chamber fills quickly tion rate is Highly applications as surface tension and possible hydro- Alternative ink pressure both phobic for:, operate to refill the print head IJ01-IJ07, nozzle. surfaces IJ10-IJ14, are IJ16, IJ20, required IJ22-IJ45

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Disad- Description Advantages vantages Examples Long The ink inlet channel Design Restricts Thermal inlet to the nozzle chamber simplicity refill rate ink jet channel is made long and Operational May result Piezoe- relatively narrow, simplicity in a lectric ink relying on viscous Reduces relatively jet drag to reduce inlet crosstalk large chip IJ42, IJ43 back-flow. area Only partially effective Positive The ink is under a Drop Requires a Silver- ink positive pressure, so selection and method brook, EP pressure that in the quiescent separation (such as a 0771 658 state some of the ink forces can be nozzle rim A2 and drop already protrudes reduced or effect- related from the nozzle. Fast refill ive hydro- patent This reduces the time phobizing, applications pressure in the nozzle or both) to Possible chamber which is prevent operation required to eject a flooding of the certain volume of ink. of the following: The reduction in ejection IJ01-IJ07, chamber pressure surface of IJ09-IJ12, results in a reduction the print IJ14, IJ16, in ink pushed out head. IJ20, IJ22, through the inlet. , IJ23- IJ34, IJ36-IJ41, IJ44 Baffle One or more baffles The refill Design HP Thermal are placed in the inlet rate is not as complex- Ink Jet ink flow. When the restricted as ity May Tektronix actuator is energized, the long inlet increase piezoelectric the rapid ink method. fabrication ink jet movement creates Reduces complex- eddies which restrict crosstalk ity (e.g. the flow through the Tektronix inlet. The slower refill hot melt process is unrestricted, Piezoe- and does not result in lectric eddies. print heads). Flexible In this method recently Significantly Not ap- Canon flap re- disclosed by Canon, reduces plicable to stricts the expanding actuator back-flow most ink inlet (bubble) pushes on a for edge- jet config- flexible flap that shooter urations restricts the inlet. thermal ink Increased jet devices fabrication complex- ity Inelastic defor- mation of polymer flap results in creep over extended use Inlet A filter is located Additional Restricts IJ04, IJ12, filter between the ink inlet advantage of refill rate IJ24, IJ27, and the nozzle ink filtration May result IJ29, IJ30 chamber. The filter Ink filter in com- has a multitude of may be fab- plex con- small holes or slots, ricated with struction restricting ink flow. no additional The filter also removes process steps particles which may block the nozzle. Small The ink inlet channel Design Restricts IJ02, IJ37, inlet to the nozzle chamber simplicity refill rate IJ44 compar- has a substantially May result ed to smaller cross section in a nozzle than that of the nozzle relatively resulting in easier ink large chip egress out of the area nozzle than out of the Only inlet. partially effective Inlet A secondary actuator Increases Requires IJ09 shutter controls the position of speed of the separate a shutter, closing off ink-jet print refill the ink inlet when the head actuator main actuator is operation and drive energized. circuit The in- The method avoids the Back-flow Requires IJ01, IJ03, let is problem of inlet back- problem is careful IJ05, IJ06, located flow by arranging the eliminated design to IJ07, IJ10, behind ink-pushing surface of minimize IJ11, IJ14, the the actuator between the nega- IJ16, IJ22, ink- the inlet and the tive pres- IJ23, IJ25, pushing nozzle. sure be- IJ28, IJ31, surface hind the IJ32, IJ33, paddle IJ34, IJ35, IJ36, IJ39, IJ40, IJ41 Part of The actuator and a Significant Small IJ07, IJ20, the act- wall of the ink reductions increase in IJ26, IJ38 uator chamber are arranged in back-flow fabrication moves so that the motion of can be complex- to shut the actuator closes off achieved ity off the the inlet. Compact inlet designs possible Nozzle In some configurations Ink back- None re- Silverbrook, actuator of ink jet, there is no flow prob- lated to EP 0771 658 does not expansion or lem is ink back- A2 and re- result in movement of an eliminated flow on lated patent ink actuator which may actuation applications back- cause ink back-flow Valve-jet flow through the inlet. Tone-jet

NOZZLE CLEARING METHOD Disad- Description Advantages vantages Examples Normal All of the nozzles are No added May not Most ink jet nozzle fired periodically, complexity be suf- systems firing before the ink has a on the print ficient to IJ01, IJ02, chance to dry. When head displace IJ03, IJ04, not in use the nozzles dried ink IJ05, IJ06, are sealed (capped) IJ07, IJ09, against air. IJ10, IJ11, The nozzle firing is IJ12, IJ14, usually performed IJ16, IJ20, during a special IJ22, IJ23, clearing cycle, after IJ24, IJ25, first moving the print IJ26, IJ27, head to a cleaning IJ28, IJ29, station. IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40,, IJ41, IJ42, IJ43, IJ44,, IJ45 Extra In systems which heat Can be Requires Silverbrook, power the ink, but do not boil highly higher EP 0771 658 to ink it under normal effective if drive volt- A2 and re- heater situations, nozzle the heater is age for lated patent clearing can be adjacent to clearing applications achieved by over- the nozzle May re- powering the heater quire and boiling ink at the larger nozzle. drive transistors Rapid The actuator is fired in Does not Effect- May be used success- rapid succession. In require extra iveness with: IJ01, ion of some configurations, drive circuits depends IJ02, IJ03, actuator this may cause heat on the print substan- IJ04, IJ05, pulses build-up at the nozzle head Can be tially upon IJ06, IJ07, which boils the ink, readily con- the config- IJ09, IJ10, clearing the nozzle. In trolled and uration of IJ11, IJ14, other situations, it may initiated by the ink jet IJ16, IJ20, cause sufficient digital logic nozzle IJ22, IJ23, vibrations to dislodge IJ24, IJ25, clogged nozzles. IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44, IJ45 Extra Where an actuator is A simple Not suit- May be used power not normally driven to solution able where with: IJ03, to ink the limit of its motion, where there is a IJ09, IJ16, pushing nozzle clearing may be applicable hard limit IJ20, IJ23, actuator assisted by providing to actuator IJ24, IJ25, an enhanced drive movement IJ27, IJ29, signal to the actuator. IJ30, IJ31, IJ32, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44, IJ45 Acous- An ultrasonic wave is A high High im- IJ08, IJ13, tic applied to the ink nozzle clear- plement- IJ15, IJ17, reson- chamber. This wave is ing capabil- ation cost IJ18, IJ19, ance of an appropriate ity can be if system IJ21 amplitude and achieved does not frequency to cause May be already in- sufficient force at the implemented clude an nozzle to clear at very low acoustic blockages. This is cost in sys- actuator easiest to achieve if tems which the ultrasonic wave is already in- at a resonant clude acous- frequency of the ink tic actuators cavity. Nozzle A microfabricated Can clear Accurate Silverbrook, clearing plate is pushed against severely mechani- EP 0771 658 plate the nozzles. The plate clogged cal align- A2 and re- has a post for every nozzles ment is lated patent nozzle. A post moves required applications through each nozzle, Moving displacing dried ink. parts are required There is risk of damage to the nozzles Accurate fabrication is required Ink The pressure of the ink May be Requires May be used pressure is temporarily effective pressure with all IJ pulse increased so that ink where other pump or series ink streams from all of the methods can- other jets nozzles. This may be not be used pressure used in conjunction actuator with actuator Expensive energizing. Wasteful of ink Print A flexible ‘blade' is Effective for Difficult Many ink jet head wiped across the print planar print to use if systems wiper head surface. The head print head blade is usually surfaces surface is fabricated from a Low cost non-planar flexible polymer, e.g. or very rubber or synthetic fragile elastomer. Requires mechan- ical parts Blade can wear out in high volume print systems Sepa- A separate heater is Can be Fabri- Can be used rate provided at the nozzle effective cation with many IJ ink although the normal where other complex- series ink boiling drop e-ection nozzle ity jets heater mechanism does not clearing require it. The heaters methods can- do not require not be used individual drive Can be im- circuits, as many plemented at nozzles can be cleared no additional simultaneously, and no cost in some imaging is required. ink jet config- urations

NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages Examples Electro- A nozzle plate is Fabrication High Hewlett Packard formed separately fabricated simplicity temperatures and Thermal Ink jet nickel from electroformed pressures are nickel, and bonded to required to bond the print head chip. nozzle plate Minimum thickness constraints Differential thermal expansion Laser Individual nozzle No masks Each hole must Canon Bubblejet ablated or holes are ablated by an required be individually 1988 Sercel et drilled intense UV laser in a Can be quite fast formed al., SPIE, Vol. 998 polymer nozzle plate, which is Some control Special Excimer Beam typically a polymer over nozzle profile equipment required Applications, pp. such as polyimide or is possible Slow where there 76-83 polysulphone Equipment are many thousands 1993 Watanabe required is relatively of nozzles per print et al., U.S. Pat No. low cost head 5,208,604 May produce thin burrs at exit holes Silicon A separate nozzle High accuracy is Two part K. Bean, IEEE micro- plate is attainable construction Transactions on machined micromachined from High cost Electron Devices, single crystal silicon, Requires Vol. ED-25, No. 10, and bonded to the precision alignment 1978, pp 1185-1195 print head wafer Nozzles may be Xerox 1990 clogged by adhesive Hawkins et al., U.S. Pat No. 4,899,181 Glass Fine glass capillaries No expensive Very small 1970 Zoltan U.S. Pat No. capillaries are drawn from glass equipment required nozzle sizes are 3,683,212 tubing. This method Simple to make difficult to form has been used for single nozzles Not suited for making individual mass production nozzles, but is difficult to use for bulk manufacturing of print heads with thousands of nozzles. Monolithic, The nozzle plate is High accuracy Requires Silverbrook, EP surface deposited as a layer (<1 μm) sacrificial layer 0771 658 A2 and micro- using standard VLSI Monolithic under the nozzle related patent machined deposition techniques. Low cost plate to form the applications using VLSI Nozzles are etched in Existing nozzle chamber IJ01, IJ02, IJ04, litho- the nozzle plate using processes can be Surface may be IJ11, IJ12, IJ17, graphic VLSI lithography and used fragile to the touch IJ18, IJ20, IJ22, processes etching. IJ24, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Monolithic, The nozzle plate is a High accuracy Requires long IJ03, IJ05, IJ06, etched buried etch stop in the (<1 μm) etch times IJ07, IJ08, IJ09, through wafer. Nozzle Monolithic Requires a IJ10, IJ13, IJ14, substrate chambers are etched in Low cost support wafer IJ15, IJ16, IJ19, the front of the wafer, No differential IJ21, IJ23, IJ25, and the wafer is expansion IJ26 thinned from the back side. Nozzles are then etched in the etch stop layer. No nozzle Various methods have No nozzles to Difficult to Ricoh 1995 plate been tried to eliminate become clogged control drop Sekiya et al U.S. Pat No. the nozzles entirely, to position accurately 5,412,413 prevent nozzle Crosstalk 1993 Hadimioglu clogging. These problems et al EUP 550,192 include thermal bubble 1993 Elrod et al mechanisms and EUP 572,220 acoustic lens mechanisms Trough Each drop ejector has Reduced Drop firing IJ35 a trough through manufacturing direction is sensitive which a paddle moves. complexity to wicking. There is no nozzle Monolithic plate. Nozzle slit The elimination of No nozzles to Difficult to 1989 Saito et al instead of nozzle holes and become clogged control drop U.S. Pat No. 4,799,068 individual replacement by a slit position accurately nozzles encompassing many Crosstalk actuator positions problems reduces nozzle clogging, but increases crosstalk due to ink surface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages Examples Edge Ink flow is along the Simple Nozzles limited Canon Bubblejet (‘edge surface of the chip, construction to edge 1979 Endo et al GB shooter’) and ink drops are No silicon High resolution patent 2,007,162 ejected from the chip etching required is difflcult Xerox heater-in- edge Good heat Fast color pit 1990 Hawkins et sinking via substrate printing requires al U.S. Pat No. 4,899,181 Mechanically one print head per Tone-jet strong color Ease of chip handing Surface Ink flow is along the No bulk silicon Maximum ink Hewlett-Packard (‘roof surface of the chip, etching required flow is severely TIJ 1982 Vaught et shooter’) and ink drops are Silicon can make restricted al U.S. Pat No. 4,490,728 ejected from the chip an effective heat IJ02, IJ11, IJ12, surface, normal to the sink IJ20, IJ22 plane of the chip. Mechanical strength Through Ink flow is through the High ink flow Requires bulk Silverbrook, EP chip, chip, and ink drops are Suitable for silicon etching 0771 658 A2 and forward ejected from the front pagewidth print related patent (‘up surface of the chip. heads applications shooter’) High nozzle IJ04, IJ17, IJ18, packing density IJ24, IJ27-IJ45 therefore low manufacturing cost Through Ink flow is through the High ink flow Requires wafer IJ01, IJ03, IJ05, chip, chip, and ink drops are Suitable for thinning IJ06, IJ07, IJ08, reverse ejected from the rear pagewidth print Requires special IJ09, IJ10, IJ13, (‘down surface of the chip. heads handling during IJ14, IJ15, IJ16, shooter’) High nozzle manufacture IJ19, IJ21, IJ23, packing density IJ25, IJ26 therefore low manufacturing cost Through Ink flow is through the Suitable for Pagewidth print Epson Stylus actuator actuator, which is not piezoelectric print heads require Tektronix hot fabricated as part of heads several thousand melt piezoelectric the same substrate as connections to drive inkjets the drive transistors. circuits Cannot be manufactured in standard CMOS fabs Complex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Water based ink which Environmentally Slow drying Most existing ink dye typicaily contains: friendly Corrosive jets water, dye, surfactant, No odor Bleeds on paper All IJ series ink humectant, and May jets biocide. strikethrough Silverbrook, EP Modern ink dyes have Cockles paper 0771 658 A2 and high water-fastness, related patent light fastness applications Aqueous, Water based ink which Environmentally Slow drying IJ02, IJ04, IJ21, pigment typically contains: friendly Corrosive IJ26, IJ27, IJ30 water, pigment, No odor Pigment may Silverbrook, EP surfactant, humectant, Reduced bleed clog nozzles 0771 658 A2 and and biocide Reduced wicking Pigment may related patent Pigments have an Reduced clog actuator applications advantage in reduced strikethrough mechanisms Piezoelectric ink- bleed, wicking and Cockles paper jets strikethrough. Thermal inkjets (with significant restrictions) Methyl MEK is a highly Very fast drying Odorous All IJ series ink Ethyl volatile solvent used Prints on various Flammable jets Ketone for industrial printing substrates such as (MEK) on difficult surfaces metals and plastics such as aluminum cans. Alcohol Alcohol based inks Fast drying Slight odor All IJ series ink (ethanol, 2- can be used where the Operates at sub- Flammable jets butanol, printer must operate at freezing and others) temperatures below temperatures the freezing point of Reduced paper water. An example of cockle this is in-camera Low cost consumer photographic printing. Phase The ink is solid at No drying time- High viscosity Tektronix hot change room temperature, and ink instantly freezes Printed ink melt piezoelectric (hot melt) is melted in the print on the print medium typically has a inkjets head before jetting Almost any print ‘waxy’ feel 1989 Nowak Hot melt inks are medium can be used Printed pages U.S. Pat No. 4,820,346 usually wax based, No paper cockle may ‘block’ All IJ series ink with a melting point occurs Ink temperature jets around 80° C. After No wicking may be above the jetting the ink freezes occurs curie point of almost instantly upon No bleed occurs permanent magnets contacting the print No strikethrough Ink heaters medium or a transfer occurs consume power roller. Long warm-up time Oil Oil based inks are High solubility High viscosity: All IJ series ink extensively used in medium for some this is a significant jets offset printing. They dyes limitation for use in have advantages in Does not cockle ink jets, which improved paper usually require a characteristics on Does not wick low viscosity. Some paper (especially no through paper short chain and wicking or cockle). multi-branched oils Oil soluble dies and have a sufficiently pigments are required. low viscosity. Slow drying Micro- A microemulsion is a Stops ink bleed Viscosity higher All IJ series ink emulsion stable, self forming High dye than water jets emulsion of oil, water, solubility Cost is slightly and surfactant. The Water, oil, and higher than water characteristic drop size amphiphilic soluble based ink is less than 100 nm, dies can be used High surfactant and is determined by Can stabilize concentration the preferred curvature pigment required (around of the surfactant. suspensions 5%) 

We claim:
 1. A method of combining image bump maps to simulate an effect of painting on an image, a method comprising: defining an image canvas bump map approximating a surface to be painted on; defining a painting bump map of a painting object to be painted on said surface; combining said image canvas bump map and said painting bump map to produce a final composited bump map, said stop of combining utilising a stiffness factor representing the stiffness of the paint in the painting bump map, to determine a degree of modulation of said painting bump map by said image canvas bump map.
 2. A method as claimed in claim 1 wherein said combining step comprises low-pass filtering said image canvas bump map to produce a low-pass filtered bump map utilising said stiffness factor to determine the degree of low-pass filtering.
 3. A method as claimed in claim 2 wherein a height of said image canvas bump map is additionally utilised in determining the degree of low-pass filtering.
 4. A method as claimed in claim 2 wherein said low-pass filtering includes utilising a filter radius to determine the degree of filtering.
 5. A method as claimed in claim 1 wherein said method is utilised in a hand held camera device to produce instant images on demand having a brushed artistic interpretation of a sensed image. 